Sew a Color 2 half square triangle to the left and to
the top of a half square unit using a 1/4" seam and
pressing seams towards the half square. Add a Color 1 half square
triangle, pressing seams towards the larger half square. This unit
should measure 3-1/2"; trim if needed. Make one more unit like
this, and two more using Color 3 half square triangles, following
the block drawing at the top of the pattern to be sure that the half
squares are oriented in the right direction...

Now place a Color 2 square right sides together and
outside edges aligned with a Color 3 3-1/2" square. Draw
a faint line on the back of the small square along the diagonal, and
sew ON this drawn line. Cut off the excess seam allowance, pressing
the remainder towards the corner. Repeat this with another Color 2
square on the other top corner. Make one more unit like this and two
more using Color 1 3-1/2" squares. This unit should
measure 3-1/2"; trim if needed.

Next sew the Color 2 1-1/2" square right
sides together to one end of a Color 1 rectangle. Stitch from a
point 1/4" away from the right bottom edge of the square to the
left edge. Press seam towards Color 1. Add a Color 3 rectangle to
the left of this, pressing towards new strip. Now add a Color 1
rectangle to the bottom, and then a Color 3 strip to the right. Fold
the top part of the block down, right sides together, to line up the
remaining un-sewn seam. Stitch from previous starting point to the
outer edge...

Now lay out all your pieced units as shown at left.
Sew three horizontal rows, pressing the top and bottom row seams
towards the center, and the middle row seams towards the outside.
Join the rows and this block is done!